When articles such as candy bars are introduced into a wrapping machine, it is important to ensure a previous elimination of excessively thick articles. During the handling of articles prior to their wrapping, a fragment of a broken article may stick to another article. Should such an article of double thickness enter the wrapping machine, serious operational disturbance may occur which conceivably can lead to the damaging of the machine, apart from the unaesthetic appearance of such a wrapped article. Heretofore the articles advancing towards the wrapping machine have been visually monitored by a worker who manually removed the articles of excessive thickness. With the increase of the output of packing machines of this type, such a monitoring operation has become more and more difficult and the danger of damage to the machine has become more increasingly greater should the worker overlook an excessively thick article. To these disadvantages one should further add the cost of labor.